Marine decking with sandwich-type construction and method of making same

ABSTRACT

A marine deck member with enhanced surface traction and the process for forming the same. The marine deck member comprises a sandwich-type composite panel made by a compression molding process. In such a process, the panel is made by subjecting a heated stack of layers of material to cold-pressing in a mold. The cellular core has a 2-D array of cells, each of the cells having an axis substantially perpendicular to the outer surfaces, and extending in the space between the layers or skins, with end faces open to the respective layers or skins. The surface traction of this type of composite panel can be enhanced for marine deck applications by controlled debossing, or embossing, of the first skin while it cools in the compression mold. The debossing effect can be effected by applying pressurized gas, e.g., pressurized air, onto the outer surface of the first skin while in the compression mold. The embossing can be effected by applying vacuum pressure on the outer surface of the first skin while in the compression mold.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. applications Ser. No.13/479,974, filed May 24, 2012 (pending), and U.S. Ser. No. 13/762,879,filed Feb. 8, 2013 (pending) the disclosures of which are herebyincorporated in their entirety by reference herein. This application isalso related to U.S. Ser. No. 14/603,418, filed Jan. 23, 2015 (now U.S.Pat. No. 9,567,037, issued Feb. 14, 2017); and Ser. No. 13/517,877,filed Jan. 14, 2012 (Abandoned).

TECHNICAL FIELD

This invention relates to marine decking for use with pontoon boats,docks, rafts, swim platforms, watercraft docking stations and the like,and methods for making the same.

BACKGROUND

The surfaces of boat decks, swim platforms, docks and similar marinestructures are commonly made of fiberglass, aluminum, treated plywood,vinyl or perforated rubber. These surfaces are subjected to sunlight/heat, rain, humidity, etc. in harsh marine service environments.These materials can deteriorate and require repair or replacement overextended periods of use.

Another factor is these materials can be slippery. Prior efforts toprovide non-slip marine surfaces are found in U.S. Pat. No. 4,737,390,for Non-Slip Coating for Molded Articles, and Pub. No. U.S.2013/0233228, for Porous Anti-Slip Floor Covering. In U.S. Pat. No.4,737,390 a layer of latex or latex-impregnated sheet material isadhered to molded thermoset plastic article while curing in the mold.FIG. 4 illustrates the application of this sheet material in a boatdeck. In Pub. No. U.S. 2013/0233228 a porous anti-slip floor coveringuses a layer of curled strands placed on an underlayment.

Factors affecting the suitability of a material for marine deckapplications, in addition to the ability to withstand the environmentalfactors above, include cost, weight, strength, traction and buoyancy.

SUMMARY

The marine deck materials of the present invention utilizesandwich-type, compression-molded, composite components. Sandwich-typecomposite panels including cores have very important characteristicsbecause of their light weight and high strength. Such panels areconstructed by sandwiching a cellular core having low strengthcharacteristics between two outer plastic layers or skins, each of whichis much thinner than the core but has excellent mechanicalcharacteristics. The core is made of a 2-D array of cells, each of thecells having an axis substantially perpendicular to the outer surfaces,and extending in the space between the layers or skins, with end facesopen to the respective layers or skins.

Sandwich-type composite panels are conventionally made by a compressionmolding process. In such a process, the panel is made by subjecting aheated stack of layers of material to cold-pressing in a mold. The stackis made up of, at least: a first skin of plastic material, a cellularcore, and a second skin also of plastic material. The stack may bepre-heated outside the mold or heated inside the mold to a softeningtemperature. Once the stack is placed in the mold, the closing of themold halves causes the inner surfaces of the softened skins to bond tothe mating faces of the core.

In one embodiment, the sandwich-type composite panel has a first skin ofthermoplastic material, a second skin of thermoplastic material, and acellular core of thermoplastic material positioned between the skins.The skins are bonded to the core by press molding. The cellular core hasa 2-D array of cells, each of the cells having an axis substantiallyperpendicular to the outer surfaces, and extending in the space betweenthe layers or skins, with end faces open to the respective layers orskins.

In another embodiment, the sandwich-type composite panel has a firstskin of a fiber-reinforced thermoplastic material, a first sheet ofthermoplastic adhesive, a second skin of fiber-reinforced thermoplasticmaterial, a second sheet of thermoplastic adhesive and a cellular coreof a cellulose-based material positioned between the skins. The skinsare bonded to the core by the first and second adhesive sheets and bypress molding. The cellular core has a 2-D array of cells, each of thecells having an axis substantially perpendicular to the outer surfaces,and extending in the space between the layers or skins, with end facesopen to the respective layers or skins.

The surface traction of this type of composite panel can be enhanced formarine deck applications by controlled (i) debossing, or (ii) embossing,of the first, outer skin while it cools in the compression mold. The airin the core cavities causes thermal gradients relative to the cell wallsthat result in uneven cooling over the surface area of the skin. Theresultant uneven cooling is manifested as “debossing” (or, “sink marks”)on the surfaces of the skins. The phenomenon of debossing can be usedadvantageously to enhance surface traction of the outer surface of thefirst skin.

The debossing effect can be accentuated by applying pressurized gas,e.g., pressurized nitrogen or air, onto the outer surface of the firstskin as it cools in the compression mold.

Alternatively, the uneven cooling phenomenon can be used to “emboss” thesurface of the skin be application of vacuum pressure while the skin iscooling in the mold. The embossments are raised surfaces that alsoenhance surface traction on the outer surface of the first skin.

The debossing/embossing pattern on the outer surface can be defined bythe cross-sectional shape of the cells. Cells of circularcross-sectional will produce circular debossments/embossments; cells ofhoneycomb shape will produce hexagonal debossments/embossments; andcells of cleated shape will produce cleat-shapeddebossments/embossments.

The invention provides marine deck materials that have a relatively highstrength-to-weight ratio, buoyancy, and enhanced surface traction. Theseproperties make these deck materials suited for use in such applicationsas boat decks, swim platforms, docks and similar marine structures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a pontoon deck as a representativeproduct application of the present invention;

FIG. 2A is an enlarged view of the pontoon deck surface, encircled as“2A” in FIG. 1, showing debossments matching the cross-sectional shapeof the circular cells in the core;

FIG. 2B is an enlarged view of a pontoon deck surface showingembossments matching the cross-sectional shape of the circular cells inthe core;

FIG. 3 is a perspective view of a swim platform or diving raft asanother representative product application of the present invention;

FIG. 4 is a perspective view of a dock as another representative productapplication of the present invention;

FIGS. 5A-C are top plan schematic views, partially broken away, ofdifferent configurations, e.g., honeycomb-like, of cellular cores;

FIG. 6 is an exploded, side sectional view showing a sandwich-typecomposite panel with a first skin of a fiber-reinforced thermoplasticmaterial, a first sheet of thermoplastic adhesive, a second skin offiber-reinforced thermoplastic material, a second sheet of thermoplasticadhesive and a cellular core of a cellulose-based material positionedbetween the skins;

FIG. 7 is an exploded, side sectional view showing a sandwich-typecomposite panel with first skin of thermoplastic material, a second skinof thermoplastic material, and a cellular core of thermoplastic materialpositioned between the skins;

FIG. 8 is a schematic, side sectional view showing a fluidpressure-assisted compression mold useful in facilitating debossing ofthe of the upper surface of the molded composite component to enhanceits surface traction;

FIG. 9 is a top perspective view, in cross section, of the compositecomponent of FIG. 6, with debossments, by application of fluid pressure;

FIG. 10 is a schematic, side sectional view showing a vacuumpressure-assisted compression mold useful in facilitating embossing ofthe of the upper surface of the molded composite component to enhanceits surface traction;

FIG. 11 is a top perspective view, in cross section, of the compositecomponent of FIG. 6, with embossments, by application of vacuumpressure;

FIG. 12 is a cross-sectional view, partially broken away, of a marinedeck member of the present invention having a fastener component mountedwithin.

DETAILED DESCRIPTION

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention that may be embodied in variousand alternative forms. The figures are not necessarily to scale; somefeatures may be exaggerated or minimized to show details of particularcomponents. Therefore, specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as arepresentative basis for teaching one skilled in the art to variouslyemploy the present invention.

FIG. 1 shows a pontoon boat 10 as a representative application of thepresent invention. The deck 12 can be composed of modular panels ortiles fitted to the surface configuration of the pontoon boat. The deck12 has mounted on it conventional surface cleats 14 to facilitatedocking. In addition to pontoon boat decks, the present invention isalso suited for other marine applications where enhanced surfacetraction is desired, for example, docks, diving boards, swim platforms,watercraft docking stations and the like.

FIG. 2A is a close-up view of the encircled portion of the pontoon deck12 of FIG. 1. The deck surface has a pattern of debossments, formed withthe assistance of pressurized gas in the process of compression moldingthe marine deck. The shape of the debossment 16 corresponds to thecross-sectional shape of the cell in the cellular core used in thecomposite molding.

FIG. 2B is a close-up view of an alternative embodiment of a pontoondeck surface 12′ showing embossments 16′ matching the cross-sectionalshape of the circular cells in the core. The embossments 16′ are formedwith the assistance of vacuum pressure in the process of compressionmolding the marine deck.

FIG. 3 shows the marine deck surfaces of the present invention appliedwith a swim platform (or diving raft) 20. The deck 12 or 12′ can beformed with debossments or embossments, respectively, as discussedbelow.

FIG. 4 shows the marine deck surfaces of the present invention appliedwith to the deck surface of a dock 22. Again, the deck 12 or 12′ can beformed with debossments or embossments, respectively, as discussedbelow.

FIGS. 5A-5C show exemplary surface shapes for the debossments andembossments to be formed in the marine deck surface, whether awatercraft deck, swim platform, dock, or other application. FIG. 5Ashows circular shapes for debossments 16C, or circular embossments 16C′.FIG. 5B shows honeycomb shapes for debossments 16H, or honeycombembossments 16H′. FIG. 5C shows rectangular shapes for debossments 16R,or rectangular embossments 16R′. The surface shape of the debossments orembossments will correspond to the cross-sectional shape of the cells inthe core of the sandwich-type structure.

FIG. 6 is an exploded side view of the constituent parts of thecomposite panel 32 preparatory to compression molding. As shown in FIG.6, a stack includes first and second reinforced thermoplastic skins orouter layers 24 and 26, respectively, a plastic core 30 having a largenumber of cells disposed between and bonded to plies or films or sheetsof hot-melt adhesive (i.e. thermoplastic adhesive) 28 which, in turn,are disposed between and bonded to the skins 24 and 26 by compressionmolding. The sheets 28 may be bonded to their respective skins 24 and 26prior to the press molding or are preferably bonded during the pressmolding. The thermoplastic of the sheets 28 is typically compatible withthe thermoplastic of the skins 24 and 26 so that a strong bond is formedtherebetween. One or more other plastics may also be included within theadhesive of the sheets 28 to optimize the resulting adhesive 24 and 26and their respective sheets or film layers 28 (with the core 30 layers28) are heated typically outside of a mold (i.e. in an oven) to asoftening temperature wherein the hot-melt adhesive becomes sticky ortacky. The mold is preferably a low-pressure, compression mold whichperforms a thermo-compression process on the stack of materials.

The sticky or tacky hot-melt adhesive 28 extends a small amount into theopen cells during the thermo-compression process. The skins 24 and 26are bonded to the top and bottom surfaces of the core 30 by the sheets28 to seal the cells of the core 30 to the facing surfaces of the skins24 and 26.

The step of applying the pressure compacts and reduces the thickness ofthe cellular core 30 and top and bottom surface portions of the cellularcore penetrate and extend into the film layers 28 without penetratinginto and possibly encountering any fibers located at the outer surfacesof the skins 24 and 26 thereby weakening the resulting bond.

Each of the skins 24 and 26 may be fiber reinforced. The thermoplasticof the sheets or film layers 28, and the skins 24 and 26 may bepolypropylene. Alternatively, the thermoplastic may be polycarbonate,polyimide, acrylonitrile-butadiene-styrene as well as polyethylene,polyethylene terphthalate, polybutylene terphthalate, thermoplasticpolyurethanes, polyacetal, polyphenyl sulphide, cyclo-olefin copolymers,thermotropic polyesters and blends thereof. At least one of the skins 24or 26 may be woven skin, such as polypropylene skin. Each of the skins24 and 26 may be reinforced with fibers, e.g., glass fibers, carbonfibers, aramid and/or natural fibers. At least one of the skins 24 and26 can advantageously be made up of woven glass fiber fabric and of athermoplastics material.

The cellular core 30 of the FIG. 6 embodiment may be a cellulose-basedhoneycomb core. In this example, the cellular core has an open-celledstructure of the type made up of a tubular honeycomb. The axes of thecells are oriented transversely to the skins 24 and 26.

The stack of material may be pressed in a low pressure, cold-formingmold 42 shown schematically in cross-section in FIG. 8. The mold hashalves 44 and 46, which when closed have an internal cavity for thestack. The stack is made up of the first skin 24, the adhesive layers28, the cellulose-based cellular core 30, and the second skin 26, and ispressed at a pressure lying in the range of 10×105 Pa. to 30×105 Pa. Thefirst and second skins 24 and 26, and the first and second film layers28 are preferably pre-heated to make them malleable and stretchable.Advantageously, in order to soften the first and second skins 24 and 26,and their respective film layers 28, heat is applied to a pre-assemblymade up of at least the first skin 24, the first and second film layers28, the cellular core 30, and the second film layer 26 so that, whilethe composite panel 32 is being formed in the mold, the first and secondskins 24 and 26 and the film layers 28 have a forming temperature lyingapproximately in the range of 160° C. to 200° C., and, in this example,about 180° C.

Air in the sealed cavities urges softened portions of the sheets 24 and26 and portions of the core 30 inwardly towards the cavities of the core30.

The mold 42 is formed with a pattern of fluid passageways 50, alignedwith the cell openings, to permit the application of fluid pressure ontothe surface of the first skin 24 from a fluid pressure source 48. Theapplied fluid pressure augments the tendency of the sheets to deboss inthe area above the cells. The pressure level and duration can beselected to determine the depth of the debossments 16 formed in theouter surface of the first skin 24. The debossments 16 enhance thesurface traction of the outer surface of the skin 24.

FIG. 9 shows a composite panel 52 with the debossments 16R formed inrectangular shapes. The cells in the core 30 are similarly rectangularin cross-section. The outer surface of the first skin 24 has enhancedsurface traction. The outer surface of the second skin 26 may benaturally debossed, but it will not be visible as part of a marine deckmember.

FIG. 8 is an exploded side view of the constituent parts of analternative embodiment of a composite panel 40 preparatory tocompression molding. In this embodiment, thermoplastic skins 34 and 36are bonded to a thermoplastic core 38 in sealed relation by heating tothe softening point of the plastic. The stack may be preheated, orheated in the mold.

The core may be injection molded by the process disclosed in U.S. Pat.No. 7,919,031, titled “Method And System For Making Plastic CellularParts And Thermoplastic Composite Articles Utilizing Same,” commonlyassigned to the assignee of the present invention.

A stack whether in the embodiment of stack 32 in FIG. 6, or the stack 40of FIG. 7, may be formed with either debossments, per the moldconfiguration of FIG. 8, or formed with embossments, per the moldconfiguration of FIG. 10.

In FIG. 10, the mold 68 is equipped with a vacuum source 66 to applyvacuum pressure through channels 70 to the outer surface of the plasticskin 24 while the skin is heated and formable in the mold.

The application of sufficient vacuum pressure causes the outer surfaceof the skin 24 to the raised with embossments 16R on the compositepanel. In this case the embossments 16R are rectangular in shape tocorrespond with the cross-sectional shape of the cells in the core 30.The outer surface of the skin 24 has enhanced surface traction due tothe embossments.

FIG. 12 shows the mounting of a fastener component 80 in the compositepanel 32. The fastener component can be used to secure cleats 14 to amarine deck formed of the inventive composite panel.

After compression or press molding, at least one hole is formed in thecomposite panel 52 such as by cutting through the first skin 24, throughthe core 30 right up to but not through the second skin 26. A rivet-likefastener such as the fastener component 80 is positioned in the hole.Each fastener component 80 is generally of the type shown in U.S. patentpublications U.S. Pat. No. 7,713,011 and 2007/0258786 wherein thepreferred fastener component is called an M4 insert, installed by use ofa hydro-pneumatic tool both of which are available from Sherex FasteningSolutions LLC of New York. During installation, an outer sleeve 44 ofthe fastener component 50 is deformed, as shown in FIG. 7.

The fastener component 80 typically has a relatively large annularflange, generally included at 82, with a plurality of integrally formedlocking formations or wedges (not shown) circumferentially spaced abouta central axis of the component 80 on the underside of the flange 82 toprevent rotary motion of the fastener component 80 relative to the firstskin 24 after installation. The wedges grip into the outer surface ofthe first skin 24 after the fastener component 80 is attached to thefirst skin 24.

A fastener 80 of the type illustrated in FIG. 12 can withstand (i) largepull-out forces, (ii) large push-in forces, and large rotational forces(torque). These performance criteria must be met while preserving themechanical and aesthetic properties of the composite panel 52.Additionally, in this use environment, the underside of the compositepanel 32 must remain impervious to moisture absorption. Moistureabsorption may result in increased weight and performance degradationover a prolonged period, especially on the underside of a marine deck.

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms of the invention. Rather,the words used in the specification are words of description rather thanlimitation, and it is understood that various changes may be madewithout departing from the spirit and scope of the invention.Additionally, the features of various implementing embodiments may becombined to form further embodiments of the invention.

What is claimed is:
 1. Decking for a marine dock having enhanced surfacetraction made by a method comprising the steps of: heating a stack ofsandwich material including first and second plastic skins and a plasticcore positioned between the skins, the core having a plurality of cellswhose axes are oriented transversely to the skins, the skins and thecore being heated to a softening temperature of the plastic; providing acompression mold including panel-forming, upper and lower dies, whichwhen closed, define a mold cavity having a shape substantiallycorresponding to a desired shape of the panel; placing the stack on thelower die in an open position of the mold; moving the dies toward eachother until the mold is in a closed position; allowing the heated stackto cool in the mold cavity in the closed position until inner surfacesof the skins are bonded to top and bottom surfaces of the core to sealthe core cells; and applying pressurized gas at a first outer surface ofthe stack in the mold cavity to facilitate debossing and enhance thesurface traction of the first outer surface.
 2. Decking for a marinedock having enhanced surface traction made by a method comprising thesteps of: heating a stack of sandwich material including first andsecond reinforced thermoplastic skins, first and second sheets ofthermoplastic adhesive and a cellulose-based core positioned between theskins and between the sheets, the core having a plurality of cells whoseaxes are oriented transversely to the skins, the skins and thethermoplastic adhesive layers being heated to a softening temperature;providing a compression mold including panel-forming, upper and lowerdies, which when closed, define a mold cavity having a shapesubstantially corresponding to a desired shape of the panel; placing thestack on the lower die in an open position of the mold; moving the diestoward each other until the mold is in a closed position; allowing theheated stack to cool in the mold cavity in the closed position untilinner surfaces of the skins are bonded by the thermoplastic adhesive totop and bottom surfaces of the core to seal the core cells; and applyingpressurized gas at a first outer surface of the stack in the mold cavityto facilitate debossing and enhance the surface traction of the firstouter surface.
 3. Decking for a marine dock having enhanced surfacetraction made by a method comprising the steps of: heating a stack ofsandwich material including first and second plastic skins and a plasticcore positioned between the skins, the core having a plurality of cellswhose axes are oriented transversely to the skins, the skins and thecore being heated to a softening temperature of the plastic; providing acompression mold including panel-forming, upper and lower dies, whichwhen closed, define a mold cavity having a shape substantiallycorresponding to a desired shape of the panel; placing the stack on thelower die in an open position of the mold; moving the dies toward eachother until the mold is in a closed position; allowing the heated stackto cool in the mold cavity in the closed position until inner surfacesof the skins are bonded to top and bottom surfaces of the core to sealthe core cells; and applying vacuum pressure at a first outer surface ofthe stack in the mold cavity to facilitate embossing and enhance thesurface traction of the first outer surface.
 4. Decking for a marinedock having enhanced surface traction made by a method comprising thesteps of: heating a stack of sandwich material including first andsecond reinforced thermoplastic skins, first and second sheets ofthermoplastic adhesive and a cellulose-based core positioned between theskins and between the sheets, the core having a plurality of cells whoseaxes are oriented transversely to the skins, the skins and thethermoplastic adhesive layers being heated to a softening temperature;providing a compression mold including panel-forming, upper and lowerdies, which when closed, define a mold cavity having a shapesubstantially corresponding to a desired shape of the panel; placing thestack on the lower die in an open position of the mold; moving the diestoward each other until the mold is in a closed position; allowing theheated stack to cool in the mold cavity in the closed position untilinner surfaces of the skins are bonded by the thermoplastic adhesive totop and bottom surfaces of the core to seal the core cells, air in thesealed cells urging softened portions of the skins inwardly towards thecells of the core as the air in the cells cools; and applying vacuumpressure at a first outer surface of the stack in the mold cavity tofacilitate embossing and enhance the surface traction of the first outersurface.
 5. A watercraft deck comprising: a compression-molded compositedeck having a sandwich structure, the deck including: a load-bearing,reinforced plastic, first outer layer; a reinforced plastic, secondouter layer; and a low density, cellular core positioned between theouter layers and having a plurality of cells wherein the outer layersand the core are bonded into a unitary structure by press molding. 6.The watercraft deck of claim 4 wherein the plurality of cells areoriented transversely to the skins and the surface traction of the firstouter layer is enhanced by applying pressurized gas onto the first outerlayer in a press molding process to facilitate debossing.
 7. Thewatercraft deck of claim 4 wherein the compression-molded compositecomponent is formed of a plurality of press-molded panels having thesandwich structure, the panels being fitted to the surface configurationof the watercraft deck.
 8. The watercraft deck of claim 4 wherein theplurality of cells are oriented transversely to the skins and thesurface traction of the first outer layer is enhanced by applying vacuumpressure on the first outer layer in a press molding process tofacilitate embossing.